Showing papers in "Mechanical Systems and Signal Processing in 1987"

TL;DR: In this paper, an existing technique for the signal processing of the time domain average of the tooth meshing vibration of gears is examined with application to the early detection of failure, and it is shown that the "regular" signal extracted from the regular signal of the gear vibration by the elimination of all except the fundamental and harmonics of the vibration of a single tooth, forms the time-domain average.

TL;DR: It is shown that the existing comb filter model of time domain averaging does not correctly describe the extraction of periodic waveforms from additive noise and a revised model is presented which requires only a finite number of samples of the signal and produces a result which is periodic.

TL;DR: In this paper, the authors developed a global modal parameter estimation technique capable of analysing frequency response functions (FRFs) between several input and response stations simultaneously, using orthogonal polynomials.

TL;DR: In this paper, the use and application of the Hilbert transform for identifying and quantifying nonlinearity associated with simulated and experimental frequency response functions is described, and the results show that both procedures give similar trends in the extracted modal parameters, with consistently lower damping estimates from the causalisation procedure.

TL;DR: In this article, the authors describe three principal flexible rotor balancing methods: modal balancing, influence coefficient balancing, and the Unified Balancing Approach, and compare them from a procedural standpoint and results from a series of comparative tests.

TL;DR: In this paper, the problem of forecasting machine failure is addressed and appropriate models and procedures are discussed, where a high power fan bearing and a railroad diesel engine are used as illustrative examples.

TL;DR: In this article, a technique based upon difference equations is described that eliminates many of the problems associated with the current methods, such as complicated curve-fitting routines and interpolative procedures.

TL;DR: In this article, frequency-based pattern recognition concepts using linear discriminant functions have been used in analysing acoustic emission signals generated during machining to distinguish between different signal sources, specifically chip formation, tool fracture, and chip noise.

TL;DR: In this paper, an adaptive observer based on force measurement is proposed, which uses both parameter and state estimation techniques to estimate tool wear in turning. But the adaptive observer requires the design of a state observer and a parameter estimator, and the suitability of the model as the basis for adaptive observation is verified.

TL;DR: In this paper, a qualitative method allowing the determination of dominant errors in a non-dissipative finite element model is presented, which is based on the simultaneous use of the orthonormal relationships satisfied respectively by the eigenmodes derived from the model and from the structure itself.

TL;DR: An improved time domain polyreference method for global model identification is presented in this paper, where a time domain preprocessing technique is developed to reduce the effects of random noise contamination on measured data.

TL;DR: In this article, the authors comment on current trends and new developments in the field of experimental modal analysis, with special emphasis on the use and limitations of recent techniques such as multiple input processing, total least square, global time and frequency domain parameter estimation.

TL;DR: The characteristics of the stepped since excitation method are briefly reviewed, for both single input and multiple input testing and the impact of this method on the estimation of the modal parameters is discussed.

TL;DR: In this paper, an integrated discussion of time and frequency domain identification method is presented, where a least square is sought in both cases, but an iterative procedure is used in the frequency domain in order to 'unweight' the least square problem.

TL;DR: It is shown that numerical problems in the estimation of the states of tool wear precludes the use of this method in multi-wear cases where both flank wear and crater wear are present, but the method can be applied when one type of wear dominates.

TL;DR: In this paper, a vibration method for measuring the contact stiffness between two bodies is described, which involves the measurement of the dynamic properties of the system comprising the two bodies, which are effectively joined by a spring, whose stiffness is the contact stiffness which is to be determined.

TL;DR: The concept of multi-triggering random decrement technique is introduced in this article, which reduces multi-mode multi-measurement stationary random responses to free decay responses but has the advantage of increasing the apparent number of the resulting free decay time response functions.

TL;DR: In this article, pattern recognition techniques are used to identify the frequencies which show a significant amount of variation in power content when the operation mode during the punching stretching process changes from plastic deformation to workpiece fracture and subsequent friction between the punch surface and the workpiece.

TL;DR: In this paper, the problem of decelerating a rotor from a high speed through its critical speeds has received very little attention in technical literature although transient processes occurring during coastdown of machinery usually provide a lot of information about their tribodynamics.

TL;DR: The systematic development of a signal processing scheme aimed at monitoring tool wear development during a specific machining process and the finally implemented scheme seem to offer viable approaches to the general task of monitoring high frequency vibrations in machine tools.

TL;DR: It is shown how the power spectral density (PSD) can still be computed for data sequences where values are either missing or suspect using straightforward techniques and not employing sophisticated interpolation procedures.

TL;DR: In this article, the problem of excessive rocking response of a large capacity railroad freight vehicle is treated by utilizing a non-linear, nine degrees-of-freedom, stochastic model, where the excitation on the system, due to the track irregularities consisting of periodic and random processes, is specified as a filtered, white noise, power spectral density function.

TL;DR: In this paper, the statistically linearized equations of motions of a railroad freight vehicle under stochastic track input derived in Part I are solved iteratively in the form of Lyapunov's equation.

TL;DR: In this article, the integration of stepped-sine excitation into a standard modal testing system is discussed, and a complete dual input test example is presented to demonstrate its application.

TL;DR: In this paper, the bending stiffness of a cross-ply composite plate is obtained through a series of dynamic tests on narrow beam-like specimens made from the plate, and a comparison is made between the experimental data and those predicted using lamination theory with static lamina properties.

TL;DR: In this article, the authors used the Fokker-planck equation to identify the non-linear characteristics of elasticity and damping properties of a mechanical system while in use.

TL;DR: In this paper, the authors describe a general purpose rotor test rig capable of handling a great number of rotor dynamics including balancing, maintenance and modal analysis of a rotor, and the most remarkable is the synchroaxle principle called SAP for short, which is described in detail.

TL;DR: In this article, a digital synchronous filtering (DSF) is proposed to estimate the time history of periodic components of the signal being analyzed, the corresponding frequencies of which are integer multiples of some triggering frequency (external or defined by the signal itself).